Large networks may contain many pieces of equipment and communication links distributed over a large geographic area, all of which must operate together in an integrated manner. Such networks not only need a network management system, but network management system generally benefit from remote or centralized control capability. A good example of this capability is the industry standard of Transmission Management Network ((TMN) that defines the function of network system operation, alarm, maintenance and provisioning (Parameter monitoring ). This industry standard was used in support of the development of the Synchronous Optical Network transmission system (SONET).
Such management systems are effective in dealing with systems where problems are mainly basic equipment faults, but they are not effective in dealing with problems that are more complex than a simple equipment failure. In radio systems, many operational conditions are transient in nature, such as weather-related, propagation, and mutual interference communication problems. Under these conditions, one does not have a steady fault to troubleshoot the network problem. For an example, point-to-point radio systems are often designed with a 20 to 40 dB transmit power margin to overcome signal fading in the propagation channel. Since there is a substantial margin under normal conditions, any degradation from interference, antenna misalignment, etc. will generally be compensated by using up a portion of margin to maintain constant performance. However, such a link will have more degradation during the increase of propagation attenuation than otherwise, and thus may experience undesirable results only upon occurrence of increased propagation attenuation. Trouble shooting of transient network conditions is extremely difficult because the environmental conditions that create the problem do not exist all the time. In order to understand the nature of the performance problem, it is necessary to measure the performance of the network while the fault is happening.
An additional problem occurs when an area is so densely populated with radio links that transmissions from one link are detected by, and interfere with, another link. Side-lobe propagation can interfere with radio receivers that are not supposed to be in the transmit path. Similarly, an antenna that becomes slightly misaligned may inadvertently point to an unrelated transmitter or receiver. Problems such as these do not involve equipment failures that can be quickly detected, and the equipment that is causing the problem is frequently not the equipment that shows degraded performance. For example, where the above mentioned transmit margin of 20 to 40 dB is utilized, the side lobes of such a misaligned antenna beam may be of sufficient magnitude to establish communications between the receiver/transmitter pair on a clear day, although a nearby link may experience disabling interference from the misdirected main lobe. An integrated analysis capability is needed to troubleshoot these types of problems.
Managing the operation and performance of radio networks involves two problems which are not addressed by conventional Parameter monitoring standards. The first is that each radio should have the capability of measuring and recording performance-related parameters in order to both provide cognizance of radio link conditions experienced as well as a knowledge base suitable for detecting changes in the radio link conditions. The second, more complex, problem is how to measure the right data at the right time in order to properly assess link conditions. For example, if one wants to measure the performance of power control, one way is to measure how constant the received power is, since the purpose of power control is to maintain the received power at a constant level. Changes in received power are frequently related to weather conditions such as rain fall density. However, 90% or more of the time the rainfall density is at or near zero (the weather is clear). So if the receive power is measured continuously, then 90% of data does not yield useful information. Since one would like the receive power to be read and recorded automatically in order to provide substantially autonomous alarm conditions or change in link or network operation, then the reading and recording rate shall be selected carefully. If a continuous rate is high enough to nearly instantaneously catch the onset of rain and any change in density thereafter, then the total amount of data may not be manageable.
What is needed is a system and method for specifying which measurements should be taken at which locations, when they should be taken, how often they should be taken, when the results should be collected, and how the results should be presented. Since the conditions that dictate some of these requirements tend to be unpredictable and transient, it is desirable to be able to dictate the measurement parameters on an as-needed basis, preferably from a centralized location.